I was looking inside my computer the other day and I have a battery on the motherboard, what’s this for and how often does it need to replaced?
The battery on the motherboard is usually a “CR2032 3 volt battery” and there are several reasons for the battery. The battery provides constant power for the PC clock, the other reason for the battery is to keep your configuration memory also know as “CMOS”, settings like the boot record and other BIOS settings can be saved.
CMOS batteries last for years, I’ve never had to replace a CMOS battery yet I usually replace the computer before I replace the battery inside my computer. You may get error messages when the battery is low “CMOS CHECKSUM FAILURE” or “CMOS BATTERY STATE LOW” that’s usually a good time to replace the battery.
Here’s a good guide on replacing the CMOS battery http://www.hardwaresecrets.com/article/81